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comparison +rv/+time/BdfDerivative.m @ 1016:4b42999874c0 feature/advectionRV

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Add lower level for boot-strapping to RungeKuttaExteriorRV - Add a lower level to RungeKuttaExteriorRV for which bootstrapping starts, e.g start bootstrapping from time level 3 using a 3rd order BDF - Clean up ResidualViscosity
author Vidar Stiernström <vidar.stiernstrom@it.uu.se>
date Fri, 07 Dec 2018 13:11:53 +0100
parents +rv/+time/BDFDerivative.m@e547794a9407
children 010bb2677230
comparison
equal deleted inserted replaced
1015:9b7fcd5e4480 1016:4b42999874c0
1 classdef BdfDerivative < handle
2 properties
3 coefficients
4 end
5 methods %TBD: Decide if the BDF order should be passed in construction
6 % and only a row of coefficients stored based on the order.
7 % There would still be an implicit dependancy on the number
8 % of vectors in v_prev and elements in coefficients.
9 % In addition, dt could be stored, but this would be
10 % inflexible if different step sizes are employed.
11 function obj = BdfDerivative()
12 obj.coefficients = obj.getBdfCoefficients();
13 end
14 % Add asserts here?
15 function DvDt = evaluate(obj, v, v_prev, dt)
16 order = size(v_prev,2);
17 DvDt = (obj.coefficients(order,1)*v - sum(obj.coefficients(order,2:order+1).*v_prev,2))/dt;
18 end
19 end
20 methods(Static)
21 function c = getBdfCoefficients()
22 c = zeros(6,7);
23 c(1,1) = 1; c(1,2) = 1;
24 c(2,1) = 3/2; c(2,2) = 4/2; c(2,3) = -1/2;
25 c(3,1) = 11/6; c(3,2) = 18/6; c(3,3) = -9/6; c(3,4) = 2/6;
26 c(4,1) = 25/12; c(4,2) = 48/12; c(4,3) = -36/12; c(4,4) = 16/12; c(4,5) = -3/12;
27 c(5,1) = 137/60; c(5,2) = 300/60; c(5,3) = -300/60; c(5,4) = 200/60; c(5,5) = -75/60; c(5,6) = 12/60;
28 c(6,1) = 147/60; c(6,2) = 360/60; c(6,3) = -450/60; c(6,4) = 400/60; c(6,5) = -225/60; c(6,6) = 72/60; c(6,7) = -10/60;
29 end
30 end
31 end